372 CHEMICAL ENGINEERING Figure 7; A considerable improvement as far as capacity is concerned is obtained by the use of tubular coils placed in the liquid to be evaporated. Large amounts of heating surface can be concentrated in a small space and this type of pan is still used to a large extent in the sugar and milk industry. Figure 8 shows the Reilly FIG. 16.—Yaryan high-speed circulation. patent evaporator, a peculiar adaption of the coil type. This evaporator is mostly used for water stills as it is claimed by the inventor that on account of the vibration of the spiral coils, the scale will not deposit on the tubes and the heating surface can be kept clean easily. FIG. 17.—Lillic film evaporator. Horizontal Type.—Figure 9 shows the first construction of an evaporator with horizontal tubes, invented and patented by Norbert Rillieux. The evaporator was used for the concentration of sugar juice in Louisiana, and is really the prototype of all modern horizontal-type evaporators. Figure 10: This construction was designed by Wellner Yelinek, and is being used to a large extent in the beet-sugar industry in this country and abroad. The same type, with a few minor changes, was patented by Swenson. Figure 11: A horizontal tube machine with a vertical cylindrical shell which was first designed by Simirenko, and later copied by Vis, and patented in the United States by Gibson and Zaremba.